Optical voltage sensors have superior alternating current (AC) electrical performance and are inherently electrically isolated. The majority of them have been used by the communication industry to couple digital signals into the vast fiber optic networks. These signals are typically AC coupled. Using the optical voltage sensor to accurately measure down to direct current (DC)/low frequencies, especially at low level signals has not had much success because the optical sensors are susceptible to changes in the surrounding environment. Temperature, mechanical stresses, and the signal applied to the optical sensor can all cause the optical output signal to shift dramatically. Also, the upstream fiber and laser source to this optical sensor can have significant polarization crosstalk, noise, etc., when subjected to the same mechanical and temperature stresses.
Thus, a need remains for addressing this DC/low-frequency instability/limitation of the sensor, upstream fiber, and laser source.